Another region command we'll look at is region-add-peer-loc, but we'll defer that until we have covered layouts.

Note that regions do not have any notion of hierarchy; they are simply "collections of devices". The hierarchy is expressed using Layouts.

Layouts

Layouts are used to define a "containment" hierarchy for the regions, as well as provide configuration information for the UI, such as which background decoration to use when displaying the layout; for example a geographical map.

A Layout is a "UI construct" that has an associated region "backing" it. Layouts (except for the "root" layout) declare their parent layout, thereby defining a hierarchy of layouts to be constructed.

The following diagram illustrates an example hierarchy:

Note that the "root" (default) layout does not have a backing region. Any devices (and their attached hosts) that have not been assigned to a region will appear in the topology view at the top level.